Cryogenic storage apparatus

ABSTRACT

970,152. Storing liquefied gases. UNION CARBIDE CORPORATION. Sept. 12, 1963 [Oct. 24, 1962], No. 35907/63. Heading F4P. A rectangular low temperature storage container comprises an outer jacket 12 composed of a solid core 21 of heatinsulating material encased in outer and inner stainless steel sheets 22a, 22b separated by an evacuable insulation space 20 from an inner vessel 14 suspended by a neck tube 16 secured to the top portion of the inner metallic sheet 22b, the neck tube being fitted with a heat insulated rectangular cover 62 (Fig. 2). The walls of the inner vessel 14 are made of relatively flexible metal sheeting reinforced by a plurality of metal partitions 30 intersecting each other to thereby divide the inner vessel 14 into a plurality of compartments closed by a sliding cover or covers 34, 36. Each wall of the outer jacket 12 is provided with bevelled edges 24a, 24b by which it is welded to an adjacent wall. The evacuable space 20 contains alternate layers of heat insulation material 56, e.g. glass wool or fibre glass sandwiched between metal, metal oxide or metal coated material. The solid core 21 of the -outer jacket 12 is preferably made of plywood, plain wood, compressed fibreboard laminate or a metallic honeycomb structure. The neck tube 16 is comprised of metal or reinforced fibrous laminate impregnated with a phenolic or an epoxy resin. The cover 62 may be vacuum insulated or comprise, as shown, a top metal sheet 64 bonded to a laminate of layers of polyurethane foam 66 alternating with aluminium sheets. To maintain the vacuum in the space 20 an absorbent 70 may be provided.

United States Patent Ofifice York Filed Oct. 24, 1962, Ser. No. 232,68514 Claims. (Cl. 62-371) This invention relates to cryogenic storagecontainers and particularly to double-walled, vacuum insulatedcontainers for storing materials at low temperatures wherein a cryogenicliquid is used as the source of refrigeration.

Low boiling liquefied gases are being increasingly used for the storageand preservation of perishable products such asfoodstuifs andbiologicals. The materials are for the most part stored in double-walledvacuum-insulated cylindrical containers. Although these containers areable to withstand the forces imposed upon the vacuum insulated wallsmore readily than a container of rectangular construction, they arerelatively unsatisfactory for pro viding maximum use of availablestorage space.

Specifically, in order to achieve the same amount of storage space as isavailable in a given size rectangular container, a cylindrically-shapedcontainer would have to be substantially larger or bulkier. The use of abox-like construction, however, presents the serious problem of makingthe walls of the box, forming the. evacuable insulation space, strongenough to carry the forces imposed by the combination of the internalatmospheric pressure of the inner box and the external atmosphericpressure and yet thin enough so that the heat leak into the box is keptto a minimum and, further, thin enough so that the weight is kept to aminimum. Also, in order to effectively utilize the storage areaavailable in a rectangular type construction, the opening for the boxshould be substantially equal to the cross-sectional area of the innerstorage area. This tends to materially increase the heat leak tothecontainer.

There have been many solutions proposed for the problem of forming highstrength double-walled vacuum box-like containers with a minimum of heatleak. One solution utilizes a foam plastic that is strong enough to actnot only as an insulating material but also as a load bearing material.The diificulty with this solution is that the heat leak through thematerial by conduction will be excessive. Another solution utilizesspacers between the two walls. Thisobviously would increase the heatleakby conduction.

It is an object of this invention to provide a doublewalledvacuum-insulated storage container of substantially uniform rectangularcross-section. Another object is to provide a rectangular double-walledcontainer having flat walls capable of withstanding pressure forceswithout the use of intermediate Wall supports. A further object is toprovide such a container with unique features that minimize its weight.Another object is to provide a container which is suitable for storingmaterial at low temperatures forprolonged periods. Another object is toprovide a container having greater accessibility to its storage area.Still another object is to provide an insulated cover for such acontainer that will aid in reducing heat transmission through thecontainer. These and other objects and advantages of this invention willbecome Patented Feb. 2, 1965 apparent from the following description andthe accompanying drawings, in which:

FIGURE 1 is a vertical cross-section through a doublewalled containerillustrating the features of the present invention;

FIGURE 2 is a vertical cross-section through a cover for the containerof FIGURE 1.

The present invention comprises a unique double-walled andvacuum-insulated storage container for storing ma terial at lowtemperatures by refrigerating the same by use of a cryogenic liquid. Thecontainer more efficiently utilizes available storage space in that ithas a substantially uniform rectangularcross-section and a rectangularopening of substantially the same size as the cross-sec tional area ofthe inner storage vessel. The inner vessel is suspended from, and solelysupported by, a neck tube which joins the top portions of the innervessel and the container outer jacket. The space between the innervessel and the outer jacket forms an evacuable insulation space.

The outer jacket is a composite structure comprising a core which issubstantially completely covered with metallic sheeting. The innervessel structure comprises a relatively flexible metallic material thatis reinforced by crossbridging the inner vessel walls so as to preventexcessive inner vessel wall deformation resulting from the pressuredifferential between the inner vessel interior and the surroundingevacuable insulation space. Inasmuch as the inner vessel is preferablyconstructed of relatively thin material to reduce the weight of thecontainer, such pressure differential could cause the walls of the innervessel to excessively deform if cross-bridging were not employed.

The container is closed by a cover constructed to fit within the necktube and designed to close the inner vessel opening such thatrefrigerant vapors escaping from the inner vessel will pass along theinner surface of the neck tube to cool the same and thereby recover thesensible refrigeration of the escaping vapor.

Referring now to the drawings and specifically to FIG- URE 1, numeral 10designates the preferred form of the container of the present invention.Container 10 com prises an outer jacket 12, an inner vessel 14, a necktube 16 which defines an inner vessel opening 18 and which, incombination with inner vessel 14 and outer jacket 12, defines anevacuable insulation space 20.

The composite outer jacket 12 is constructed of a core material 21 thatis substantially completely covered with metallic sheeting 22. Core 21is preferably constructed of laminated material such as plywood orMasonite, unlaminated plain wood such as maple or a suitable metallichoneycomb structure. Flexible supporting metallic sheeting 22 ispreferably constructed of stainless steel and bonded to the inner andouter surfaces of core 21 by means of a suitable adhesive.

Outer jacket 12 is preferably constructed of separate sheets of corematerial, each -of which constitutes a wall of the outer jacket. Whenouter jacket 12 is constructed of separate sheets, it is preferable thateach outer jacket wall be beveled about its periphery as shown in FIG. 1so that load bearing surfaces such as 24a and 24b may be providedbetween adjacent walls to increase the structural rigidity of container10. It is also preferable that each outer jacket wall be encased inseparate pairs of metal sheeting such as 22a and 22b which substantiallycompletely enclose a corresponding outer jacket wall. Adjacent interiormetal sheets 22b are preferably welded together to provide a gas-tightouter wall for evacuable insulation space 20. Spaces 26 are preferablyprovided along the edges of the outer jacket wall peripheries so thatsuch welding may be accomplished without damaging the core structure ofouter jacket 12. The corners and top rim of outer jacket 12 arepreferably protected by metallic strips 28.

Inner vessel 14 is constructed of relatively flexible thinwalledmetallic sheeting and reinforced against excessive wall deformation .dueto the pressure differential across the inner vessel walls, bycross-bridging the inner vessel walls. Such cross-bridging is preferablyprovided by intersecting metallic sheets 30 each of which have one endrigidly connected to the inner surface of an inner vessel wall and anopposite end rigidly connected to the other metal sheets through avertical support member 32. The choice of the number and the-positioningof these metal sheets 30 depends on the reinforcing requirements ofinner vessel 14 and on the number of vertically-divided compartmentsformed by the intersecting metal sheets 30 that are desired. 7 I

The pressure differential between the ambient atmosphere and the lowpressure in evacuable insulation space 20 is'compensated by the rigidityof the composite Wall of core 21 and the metallic sheeting 22 and thesuspension of inner vessel 14 therefrom. Thus, the forces imposed onouter jacket 12 from such pressure differential are car-l ried Withoutthe aid of intermediate spacers bridging evacuable insulation space 20;The use of intermediate spacers would result in greater heat ,leak intoinner vessel 14 and is therefore not desirable. Further, because of theinner vessel wall cross-bridging, the innerxvessel walls work togetherto resist the tendency to deform excessively as a result of theevacuation of insulation space 20. This materially aids in minimizingthe Weight of container 10 in that the inner vessel walls maybeconstructed of thinner material.

Thecompartments of inner vessel 14 are preferably closed by covers suchas sliding covers 34 and 36, al. though a single cover could be used.These covers permit access to a desired compartment without exposingother compartments to the atmosphere when container '10 is opened onremoval of the containercover. Sliding covers 34 and 36 arepreferablysupported and guided by channel members such as 38, 40, and .42 whichareconnected to the upper portion of inner vessel 14' above metal sheets30.

It is preferred that sliding covers 34 and 36 be constructed of aluminumin order to reduce thermal radiation into inner vessel 14.

Neck tube 16 may be constructed of a thin metallicmaterial, or asubstantially gas impervious reinforced fibrous laminate impregnatedwith a thermosetting resin, examples of which are reinforced phenolicand epoxy resins. Neck :tube 16 is preferably connected to outer jacket12 by reinforcing angle 44 having a downwardlypositioned apex. Anglemember 44 is welded to the upper load bearing surfaces as shown at 24c:and 24d and to an upper neck tube reinforcing strip 46. It has beenfound to be preferable to employ anangle member in an inverted positionas shown at 44 rather than achannel member of a member of some otherconfiguration. Angle 44 is easier to fit into place and in additionprovides. a convenient and protected space for the vacuum pinch-off tube48 and also provides greater strength at'less weight.

Neck tube '16 maybe additionally reinforced by lower neck tubereinforcing strip 50 and by neck tube corner reinforcements such asangles 52 and 54, the legs of such anglesbeing preferably welded to theinner surface of neck tube 16. Inasmuch as it is preferable to constructneck tube 16 of relatively thin material so as to reduce heat leaktherethrough, the above-mentioned reinforcements may be insufficient inwhich case it would bepreferable 'to fasten a low-thermally conductivematerial (not 4 shown) such as polyurethane foam plastic to the exteriorsurface of neck tube- 16. Such plastic would be bonded to the outersurface. of neck tube 16 by a suitable adhesive and would preferablyextend across the width of evacuable insulation space 20.

In its preferred form, container 10 employs thermal insulation 56 inevacuable insulation space 20 to reduce heat leak therethrough.Preferably, opacified insulation of the alternate layer type describedin' US. Patent 3,007,596 issued to L. C. Matsch is employed. Thisinsulation comprises alternate layers of a low heat conductive materialand thermal radiation impervious barriers. Examples of the low heatconductive material, which may be produced in sheet, form, includefilamentary glass material such as glass-wood and fiber, glass. Thespaced radiation barriers may comprise eithera metal, metal oxide, ormetal coated material, such as aluminum coatedplastic film, or otherradiation adsorptive material. Radiation reflective material comprisingthin metal foils are particularly suited in the construction of thepresent invention. When fiber sheets .areemployed as the low conductivematerial, they may additionally serve .as a support means for therelatively fragile radiation impervious sheets.

Notwithstanding the employment. of inner vessel wall cross-bridging,there will be some outward deformation of the inner. vessel walls.Therefore, opacified insulation 56 must be so arranged withinxevacuableinsulation-space 20 so that such deformation will not unduly compressthe insulation. To provide against such undue compression, it ispreferred that a space he leftfbfitWCEn the insulation material and theouter wall of evacuable insulation space 20 as shown at 5-8 and 60 toallow for such deformation.

' tion thereof asshown inFIG. 1 so that =anexcessive amount of theconductive radiation impervious barriers will not be in close proximityto the top of container 10 which is at substantiallyambient-temperature.

In fabricating container 10, inner'vessel14 and neck tube 16 are firstcompletely fabricated with the alternate layer opacified insulation 56preferably tightly installed about the outer surface of inner vessel 14by taping or other suitable means. 7 Inner vessel 14' is suspended in Icontainer 10-fromthe top portion of outer jacket 12 through neck tube 16by welding the latter to outer jacket 12 as shown in FIG. -1.Evacuableinsulation space 20 is then evacuated resulting in someunavoidable outward deformation of the inner vessel walls. Because ofthe inner vessel wall cross-bridging, the deformation will not be'excessive. Thus, although insulation 56 may now substantially fillevacuable insulation space .20 because .of this inner vessel walldeformation, it will not be unduly compressed. Such undue compressionwould deleteriously increase theheat leakage into inner vessel '14through the insulationmaterial and is highly undesirable.

To achieve maximum utilization .of the storage space in inner vessel'14,: the'opening thereto through neck tube 16 should have substantiallythe same cross-section as that of inner vessel 14. An opening of thisrelative size creates the problem of properly. insulating by means of asuitable cover, what is otherwise a largev uninsulated area comprisingabout Ms of the container surface. The cover used with container "10 isparticularly adaptable for insulating such areas. This cover is shown inFIG. 2.

Referring to FIG..2, cover 62 preferably comprises a top metal sheet64'bonded to layers of insulation material 66 which are separatedby-thin metallic sheets .68. A suitable insulation material, "is aunicellular foam plastic such as polyurethane. Metallic sheets 68,'-preferably constructed of aluminum, act asthermal radiation barriers toreduce the passage of infrared rays without significantly increasing:the thermal conductivity of cover-62." A more important function ofmetallic-sheets 68 is to act as lateral thermal conductors such thatheat will be conducted through the sheets 68 and absorbed by escapingrefrigerant vapors passing between cover 62 and neck tube 16 when thecover is installed in neck tube 16. Since the metallic sheets 68 conductheat radially out of the cover 62, the greater the number of such sheets68, the more effective will cover 62 be in reducing heat leak. However,an excessive number of metallic sheets 68 will cause the insulationmaterial 66 to lose its effectiveness. Use of plastic as the insulationmaterial 66 permits sectionalizing cover 62 if desired to correspond tothe number and size of the inner vessel storage compartments.Alternatively, cover 62 could be of the vacuum-insulated type to provideeven greater protection against heat leak, or constructed entirely ofthe aforementioned plastic.

If the length of container is sufliciently great, it may be necessary toreinforce the top of the outer jacket walls against deformation becauseof the beam length of the longer panels. Such reinforcing may beaccomplished by positioning suitable support members across the top ofcontainer 10 between outer jacket walls. Where this is done,sectionalization of cover 62 is particularly useful.

To aid in the maintenance of the vacuum in insulation space 20, amolecular sieve adsorbent 70 is preferably employed in the mannerdescribed in US. Patent 2,900,- 800 issued to P. E. Loveday. The bottomwall of inner vessel 14 may be constructed in the form of an invertedpan for covering the adsorbent 70 which may be held in place by a glasscloth (not shown) providing gas communication between adsorbent 70 andevacuable insulation space 20.

When only a portion of the storage space is utilized, or where thematerial stored is to be kept away from the refrigerant in inner vessel14, an inverted pan (not shown) may be placed on the bottom wall ofinner vessel 14 for such material.

As an illustration of the manner in which the embodiment of thisinvention shown in FIGURES 1 and 2 might be utilized, consider thefollowing. Liquid nitrogen may be transferred from a storage vessel intothe container storage space defined by inner vessel 14. On sliding cover36 beneath cover 34, to expose the inner vessel storage space, thematerial to be stored, such as biologicals, are then inserted into theinner vessel and immersed in the liquid nitrogen. Sliding cover 36 isnow returned to position and the container cover 62 is inserted into thecontainer opening 18. Whenever it is desired to remove any of the storedmaterial, cover 62 is removed and one of the sliding covers 34 or 36 ispositioned to expose the inner vessel storage space and the materialremoved through the opening to the inner vessel so provided.

Although preferred embodiments of the invention have been described indetail, it is contemplated that modifications thereof may be made andthat some features may be employed without others, all within the spiritand scope of the invention.

What is claimed is:

l. A low temperature storage container having spaced outer jacket andinner vessel walls with an evacuable insulation space therebetweencomprising in combination: composite outer jacket bottom and side wallsconstructed of a core material and metallic sheeting substantiallycompletely covering the exterior and interior surfaces of said corematerial and bonded thereto to form an outer jacket of substantiallyuniform rectangular cross-section for the container, the metallicsheeting being constructed to form a gas-tight outer wall of saidevacuable insulation space; an inner vessel of substantially uniformcross-section within said container comprising bottom and side wallsconstructed of relatively flexible metallic sheeting and adapted tocontain a vaporizable refrigerant; a neck tube of substantially the samecross-section as said inner vessel gas-tightly constructed and joined tothe top portions of said outer jacket and said inner vessel to suspendthe latter from the former; the inner vessel side and bottom walls andsaid neck tube being constructed to form a gas-tight inner wall of saidevacuable insulation space; inner vessel wall cross-bridging meanswithin said inner vessel constructed to prevent excessive inner vesselwall deformation resulting from the pressure differential between theinner vessel interior and the surrounding evacuable insulation space;cover means comprising top and bottom walls of substantially rectangularcross-section and insulation means disposed therebetween, said covermeans being constructed to loosely fit within said neck tube and closethe container opening defined by said neck tube such that refrigerantvapors escaping from said inner vessel pass along the inner surface ofsaid neck tube and cool said inner surface thereby recovering therefrigerating effects of such vapor.

2. A low temperature storage container according to claim 1 wherein thebottom and side walls of said outer jacket comprise separate sheets ofmaterial and the outer jacket metal sheeting comprises separate pairs ofmetal sheets, each of such pairs substantially completely enclosing acorresponding outer jacket wall.

3. A low temperature storage container according to claim 1 wherein theinner vessel wall cross-bridging means comprise metal sheets, eachhaving one end rigidly connected to the inner surface of an inner vesselwall and being constructed to vertically subdivide the interior of saidinner vessel into compartments.

4. A low temperature storage container according to claim 1 wherein thecontainer cover insulating means disposed between the top and bottomwalls of said cover means comprises layers of low thermally conductivematerial, and thin high thermally conductive radiation impervious sheetsseparating the low thermally conductive layers.

5. A low temperature storage container according to claim 2 wherein theseparate sheets which comprise the outer jacket bottom and side wallshave beveled peripheries constructed to provide load bearing surfacesbetween separate sections of said outer jacket.

6. A low temperature storage container according to claim 1 wherein saidevacuable insulation space is substantially filled with thermalinsulation.

7. A low temperature storage container according to claim 1 wherein saidevacuable insulation space is substantially filled with thermalinsulation comprising alternate layer opacified insulation material.

8. A low temperature storage container according to claim 1 wherein thecover means is constructed in sections and the container coverinsulating means disposed between the top and bottom walls of said covermeans comprises layers of low thermally conductive material, and thinhigh thermally conductive radiation impervious sheets separating the lowthermally conductive layers.

9. A low temperature storage container according to claim 1 wherein thecover means is vacuum insulated.

10. A low temperature storage container according to claim 1 includingouter jacket support member positioned across the top of the containerto resist beam deformation of the outer jacket walls.

11. A low temperature storage container according to claim 1 whereinsaid evacuable insulation space is substantially filled with thermalinsulation comprising alternate layer opacified insulation material,such opacified insulation material being arranged in said evacuableinsulation space to prevent undue compression thereof due to outwarddeformation of the inner vessel walls by providing a space between suchinsulation and said outer jacket.

12. A low temperature storage container according to claim 1 whereinsaid evacuable insulation space is substantially filled With thermalinsulation comprising alternate layer opecified insulation material,such opacified insula- '2' tion being tapered'at the top portion of saidinsulation space.

13. A low temperature storage container accordingto claim-1 wherein saidneck tube isconnected to said outer jacket by means of an angle memberhaving a downwardly positioned apex. 1

14. A low temperature storage container according to claim 1 whereinsaid neck tube is constructed from a gas impervious reinforced fibrouslaminate impregnated with a thermoset synthetic resin.

References Cited in the file of this patent UNITED STATES PATENTS1,256,162 Patee Feb. 12, 1918 8 Glennan Aug. 30, Richmond Nov. 15, OwensSept. 12, Williamsonet a1. Jam 2, Freedman June 23, Rupp Aug. 4,Morrison July 14, Morrison,. Jan. 24, Telks June'27, Brown 1 Dec. 25,

Morrison Aug. 20,

1. A LOW TEMPERATURE STORAGE CONTAINER HAVING SPACED OUTER JACKET ANDINNER VESSEL WALLS WITH AN EVACUABLE INSULATION SPACE THEREBETWEENCOMPRISING IN COMBINATION: COMPOSITE OUTER JACKET BOTTOM AND SIDE WALLSCONSTRUCTED TO A CORE MATERIAL AND METALLIC SHEETING SUBSTANTIALLYCOMPLETELY COVERING THE EXTERIOR AND INTERIOR SURFACES OF SAID COREMATERIAL AND BONDED THERETO TO FORM AN OUTER JACKET OF SUBSTANTIALLYUNIFORM RECTANGULAR CROSS-SECTION FOR THE CONTAINER, THE METALLICSHEETING BEING CONSTRUCTED TO FORM A GAS-TIGHT OUTER WALL OF SAIDEVACUABLE INSULATION SPACE; AN INNER VESSEL OF SUBSTANTIALLY UNIFORMCROSS-SECTION WITHIN SAID CONTAINER COMPRISING BOTTOM AND SIDE WALLSCONSTRUCTED OF RELATIVELY FLEXIBLE METALLIC SHEETING AND ADAPTED TOCONTAIN A VAPORIZABLE REFRIGERANT; A NECK TUBE OF SUBSTANTIALLY THE SAMECROSS-SECTION AS SAID INNER VESSEL GAS-TIGHTLY CONSTRUCTED AND JOINED TOTHE TOP PORTIONS OF SAID OUTER JACKET AND SAID INNER VESSEL TO SUSPENDTHE LATTER FROM THE FORMER; THE INNER VESEL SIDE AND BOTTOM WALLS ANDSAID NECK TUBE BEING CONSTRUCTED TO FORM A GAS-TIGHT